The ultimate long-term objectives of this project are to fully describe and quantify the extent of chemosensory functional decline in the elderly, to understand its etiology, and to identify in the chemical senses processes which may be common to aging of other sensory systems. Studies conducted during the current grant period have provided important, new information about chemosensory function in the aged as well as raised a number of provocative questions which have never been posed before. Thus, the specific aims of the current proposal are 1) to aggressively pursue the longitudinal study of chemosensory aging begun during the current grant period assessing the rates of decline both within and across chemosensory functions, at different levels of the systems; and 2) to conduct a series of highly-related, cross-sectional studies which will investigate aspects of potential precursors of olfactory dysfunction in the aged; probe for changes in the hedonics of chemosensory stimuli over time in aging persons; investigate new aspects of odor memory and cognition in the elderly; examine the relationship between olfactory function and age-related changes in cerebral structure on MRI; and compare rates, degree and pattern of recovery from olfactory dysfunction in children and older adults. Subjects in the studies of normal aging will be active, non-institutionalized persons in good nasal health and without dementia. They will be drawn from several age groups: from young adults through the oldest-old. Additional subjects will be a group of patients (children and older adults) with head trauma. A multi-faceted approach, employing both classical and modern psychophysical techniques, will be used to assess identification, odor recognition and recall memory paradigms and scaling of hedonics. Cognitive function will be assessed by standard intelligence and neuropsychological tests. Nasal airway resistance will be measured by anterior rhinomanometry. Nasal disease will be assessed by ear, nose and throat examinations, including endoscopy and nasal cytology. Structural changes in the brain will be assessed by MRI. A more complete understanding of chemosensory function in the elderly may suggest methods for maintaining function in old age, maximizing chemosensory perception, food palatability, and nutritional status in the geriatric population. These studies have the potential to both aid in enhancing quality of life in the aging population and to increase understanding of life-span chemosensory function and dysfunction.